Improvement in valves for steam-engines



E. COPE 8: J. R. MAXWELL. Valve for Steam-Engines.

No. 202,933. Patented April 30, I878.

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N. PETERS, PHOIO-LITHOGRAFHER, WASHINGTON D C UNITED STATES PATENTOFFICE.

EZRA COPE, OF HAMILTON, AND JAMES R. MAXWELL, OF CINCINNATI, OHIO.

IMPROVEMENT lN VALVES FOR STEAM-ENGINES.

Specification forming part of Letters Patent No. 202,933, dated April30, 1878; application filed August 31,1876.

To all whom it may concern:

Be it known that we, EZRA COPE, of the city of Hamilton, county ofButler, and JAMES R. MAXWELL, of the city of Cincinnati, county ofHamilton, all in the State of Ohio, have invented certain new and usefulImprovements in Valves for Steam-Engines; and we declare that thefollowing is a full, clear, and exact description thereof, referencebeing had to the accompanying drawings, which form a part of thisspecification.

Our invention relates to certain improvements in steam pumping-engines,patented by Robt. Allison, September 29, 1868, numbered 82,475, andreissued August 3,1869, numbered 3,573, in which the motion of thesteam-valves is controlled and regulated by a cataract.

Our invention consists of an arrangement of parts, in combination withacataract, whereby the valve motion is rendered more positive, and1 theengine perfectly safe under variable The figure of the drawings is alongitudinal section through the cylinder, steam chest, and valves ofour improvement, in which the main piston, by means of a lever, impartsa positive motion to a movable cataract-cylinder, the auxiliary cylinderbeing stationary and the auxiliary piston steam-1noved.

Like parts are indicated by the same letters, and arrows show thedirection of the moving parts and the flow of steam.

A is the main steam-cylinder; B, the main piston, and O the steam-chest.D is the main valvein all cases a plain slide-valve. C is a stationaryauxiliary cylinder. D is an auxiliary piston, operating in the auxiliarycylinder, moved by the direct pressure of steam, and moving the mainvalve by direct attachment or contact. F is the auxiliary valve, foradmitting steam to the auxiliary cylinder to move the auxiliary piston.It may be moved, as shown in the drawings, by the contact of an armattached to the movable cataractcylinder, with tappets on its rod, andplaced in an auxiliary. chest, F or it may be moved directly by thelever I or it may be placed in the main chest without motion of its own,being carried upon the auxiliary cylinder imtil it is brought intocontact with one of the studs, F. The communication of the ports is thenestablished by the passage of the auxiliary cylinder under the valve.

G is a small piston, working in a cylinder, H, filled with oil, water,or other suitable liquid, and fully described in the patent of Allison,above referred to. The piston is connected by a rod to the auxiliarypiston, controlling and regulating its motion, and hence the motion ofthe main valve.

I and I are levers and connecting-rods, operated by an arm, J, attachedto the main piston-rod, and imparting motion to the auxiliary orcataract cylinders. The main valve is placed in an independentsteam-chest, and attached to the auxiliary piston D by the rod D ,whichis also attached to the cataract-piston G. Steam enters the main chestat S, and passes to the auxiliary chest through the passage 8. Theauxiliary valve F being moved, as we have shown, admits steam to theauxiliary cylinder 0 through the ports 0 and e, forcing the auxiliarypiston, and hence the cataract-piston and main valve, to the right andleft alternately.

The cataract-piston maintains this motion at a uniform velocity duringthe entire travel. By means of the valve L in the passage leading fromend to end of the cataract-cylinder, this velocity of the cataract andauxiliary pistons may be varied to suit the circumstances and conditionsunder which the engine is required to work. The motion thus imparted tothe main valve carries it off the steam-admission port, admitting steamto either end of the main cylinder alternately. As soon as thesteam-port is opened wide enough to admit sufficient steam, the mainpiston will commence its stroke, and at once commences to draw thecataract-cylinder H, by means of the lever I, in a direction opposite toits own; hence the cataract-cylinder H and piston G are moving inopposite directions.

The liquid with which the cataract-cylinder is filled being practicallyincompressible, the motion of cataract-cylinder will act, through thecataract-piston, upon the main valve and auxiliary piston, causing thevalve to open or close the steam-admission port, according to thevelocity with which the main piston is moving. For instance, if theauxiliary piston has commenced to travel to the left, carrying with itthe main valve and cataract-piston, at the ve 2 manta looity permittedby the flow of liquid in the cataract-cylinder, the main steam-port Awill be opened. The main piston then commences its stroke to the left,and, by means of the lever I, will commence to move the cataractcylinderH to the right. Now, if the velocity of the cataract-cylinder justequalsthe velocity of the auxiliary and cataract pistons, the form er movingto the right as fast as the latter move to the left, as will occur whenthe main piston maintains a uniform speed, the effect of the one motionupon the valve will be counteracted by the other, and hence the valvewill remain stationary, admitting a constant and equal supply of steamto the main cylinder during the entire stroke of its piston.

Should the velocity of the main piston be accelerated, thecataract-cylinder will be forced to the right faster than the auxiliarypiston is moving to the left; consequently the latter will be forced tothe right, compressing the steam in the auxiliary cylinder, and carryingthe main valve to the right, until the admission of steam to the maincylinder is nearly or quite cut off. The main piston will then move onat its normal speed to the end of its stroke, or will come to rest untilthe auxiliary piston has again carried the valve off the steam-admissionport. On the other hand,

should the speed of the main piston be retarded, the cataract-cylinderwill be moved to the right more slowly than the auxiliary piston ismoving to the left; hence the latter will carry the main valve to theleft, opening the steam-admission port wider, admitting an additionalsupply of steam to the main cylinder, to carry the main piston to theend of its stroke at its normal speed. The main valve is thus moved bythe combined motions of the main and auxiliary pistons, producing adifferential motion of the valve, which varies the distribution of steamto the main cylinder with each variation of load upon the main piston.

Having thus fully described our invention, what we claim as new, anddesire to secure by Letters Patent, is-

The combination of movable cataract-cylinder H and piston G, thestationary auxiliary cylinder C and piston D, and the main valveD, theauxiliary piston moving the main valve in a direction to admit steam tothe main cylinder, and the cataract-cylinder H moving it in a directionto cut off steam, whereby the main valve becomes a regulating andcut-off valve, substantially as shown and described.

EZRA COPE. J. R. MAXWELL.

Witnesses:

ROBT. CULLIN, I J. R. PADDACK.

